Thermoregulation

• What is an endotherm?

  An endotherm is an organism that generates heat internally to maintain a constant body temperature.
• How do structural features affect heat exchange?

  Brown adipose tissue have an increased number of mitochondria per cell therefore better insulation.
• List the behavioural responses that effect thermoregulation?

  Kleptothermy, hibernation, aestivation, and torpor.
• Describe kelptothermy.

  The tendency of some organisms to share body temperature often occurs through huddling.
• Describe hibernation?

  Is an extended torpor, lasts for weeks and results in body temperature and metabolic rate lowering to a level that just supports life.
• Describe aestivation?

  A light seasonal dormancy during high temperatures and dry conditions.
• Describe torpor.

  The condition in which organisms slow their metabolic rate and reduce their body temperatures, typically for only several hours.
• List the physiological mechanism.

  Vasomotor control, evaporative heat loss, counter current heat exchange, and thermogenesis/metabolic activity.
• Describe vasomotor control.

  Through vasodilation - blood vessel expansion during hot periods – reduces body temperature.

  Through vasoconstriction - blood vessel constriction occurs during cold periods as blood is brought away from the skin – can become frostbite.
• List the homeostatic mechanisms?

  Thyroid hormones and insulin.
• Describe thyroid hormones.

  Low body temperatures are detected by the hypothalamus, result in release of thyroxine, a hormone that increase metabolic rate.
• Describe insulin?

  During hypothermia, insulin is released causing higher levels of blood sugar, these higher blood sugar levels allow for greater cellular respirations.